@article{LaquaiSchauppGriescheetal.2022,
  author    = {Laquai, Ren{\´e} and Schaupp, Thomas and Griesche, Axel and M{\"u}ller, Bernd R. and Kupsch, Andreas and Hannemann, Andreas and Kannengiesser, Thomas and Bruno, Giovanni},
  title     = {Quantitative analysis of hydrogen-assisted microcracking in duplex stainless steel through X-ray refraction 3D imaging},
  series = {Advanced engineering materials},
  volume    = {24},
  journal   = {Advanced engineering materials},
  number    = {6},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1527-2648},
  doi       = {10.1002/adem.202101287},
  pages     = {10},
  year      = {2022},
  abstract  = {While the problem of the identification of mechanisms of hydrogen-assisted damage has and is being thoroughly studied, the quantitative analysis of such damage still lacks suitable tools. In fact, while, for instance, electron microscopy yields excellent characterization, the quantitative analysis of damage requires at the same time large field-of-views and high spatial resolution. Synchrotron X-ray refraction techniques do possess both features. Herein, it is shown how synchrotron X-ray refraction computed tomography (SXRCT) can quantify damage induced by hydrogen embrittlement in a lean duplex steel, yielding results that overperform even those achievable by synchrotron X-ray absorption computed tomography. As already reported in the literature, but this time using a nondestructive technique, it is shown that the hydrogen charge does not penetrate to the center of tensile specimens. By the comparison between virgin and hydrogen-charged specimens, it is deduced that cracks in the specimen bulk are due to the rolling process rather than hydrogen-assisted. It is shown that (micro)cracks propagate from the surface of tensile specimens to the interior with increasing applied strain, and it is deduced that a significant crack propagation can only be observed short before rupture.},
  language  = {en}
}
@article{ManiKupschMuelleretal.2022,
  author    = {Mani, Deepak and Kupsch, Andreas and M{\"u}ller, Bernd R. and Bruno, Giovanni},
  title     = {Diffraction Enhanced Imaging Analysis with Pseudo-Voigt Fit Function},
  series = {Journal of imaging : open access journal},
  volume    = {8},
  journal   = {Journal of imaging : open access journal},
  number    = {8},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2313-433X},
  doi       = {10.3390/jimaging8080206},
  pages     = {13},
  year      = {2022},
  abstract  = {Diffraction enhanced imaging (DEI) is an advanced digital radiographic imaging technique employing the refraction of X-rays to contrast internal interfaces. This study aims to qualitatively and quantitatively evaluate images acquired using this technique and to assess how different fitting functions to the typical rocking curves (RCs) influence the quality of the images. RCs are obtained for every image pixel. This allows the separate determination of the absorption and the refraction properties of the material in a position-sensitive manner. Comparison of various types of fitting functions reveals that the Pseudo-Voigt (PsdV) function is best suited to fit typical RCs. A robust algorithm was developed in the Python programming language, which reliably extracts the physically meaningful information from each pixel of the image. We demonstrate the potential of the algorithm with two specimens: a silicone gel specimen that has well-defined interfaces, and an additively manufactured polycarbonate specimen.},
  language  = {en}
}
@article{ChenMuellerPrinzetal.2020,
  author    = {Chen, Cong and M{\"u}ller, Bernd R. and Prinz, Carsten and Stroh, Julia and Feldmann, Ines and Bruno, Giovanni},
  title     = {The correlation between porosity characteristics and the crystallographic texture in extruded stabilized aluminium titanate for diesel particulate filter applications},
  series = {Journal of the European Ceramic Society},
  volume    = {40},
  journal   = {Journal of the European Ceramic Society},
  number    = {4},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0955-2219},
  doi       = {10.1016/j.jeurceramsoc.2019.11.076},
  pages     = {1592 -- 1601},
  year      = {2020},
  abstract  = {Porous ceramic diesel particulate filters (DPFs) are extruded products that possess macroscopic anisotropic mechanical and thermal properties. This anisotropy is caused by both morphological features (mostly the orientation of porosity) and crystallographic texture. We systematically studied those two aspects in two aluminum titanate ceramic materials of different porosity using mercury porosimetry, gas adsorption, electron microscopy, X-ray diffraction, and X-ray refraction radiography. We found that a lower porosity content implies a larger isotropy of both the crystal texture and the porosity orientation. We also found that, analogous to cordierite, crystallites do align with their axis of negative thermal expansion along the extrusion direction. However, unlike what found for cordierite, the aluminium titanate crystallite form is such that a more pronounced (0 0 2) texture along the extrusion direction implies porosity aligned perpendicular to it.},
  language  = {en}
}
@article{LaquaiMuellerSchneideretal.2020,
  author    = {Laquai, Rene and M{\"u}ller, Bernd R. and Schneider, Judith Ann and Kupsch, Andreas and Bruno, Giovanni},
  title     = {Using SXRR to probe the nature of discontinuities in SLM additive manufactured inconel 718 specimens},
  series = {Metallurgical and Materials Transactions A},
  volume    = {51},
  journal   = {Metallurgical and Materials Transactions A},
  number    = {8},
  publisher = {Springer},
  address   = {New York},
  issn      = {1073-5623},
  doi       = {10.1007/s11661-020-05847-5},
  pages     = {4146 -- 4157},
  year      = {2020},
  abstract  = {The utilization of additive manufacturing (AM) to fabricate robust structural components relies on understanding the nature of internal anomalies or discontinuities, which can compromise the structural integrity. While some discontinuities in AM microstructures stem from similar mechanisms as observed in more traditional processes such as casting, others are unique to the AM process. Discontinuities in AM are challenging to detect, due to their submicron size and orientation dependency. Toward the goal of improving structural integrity, minimizing discontinuities in an AM build requires an understanding of the mechanisms of formation to mitigate their occurrence. This study utilizes various techniques to evaluate the shape, size, nature and distribution of discontinuities in AM Inconel 718, in a non-hot isostatic pressed (HIPed) as-built, non-HIPed and direct age, and HIPed with two step age samples. Non-destructive synchrotron radiation refraction and transmission radiography (SXRR) provides additional information beyond that obtained with destructive optical microscopy. SXRR was able to distinguish between voids, cracks and lack of melt in, due to its sensitivity to the orientation of the discontinuity.},
  language  = {en}
}
@article{CabezaMuellerPereyraetal.2018,
  author    = {Cabeza, Sandra and M{\"u}ller, Bernd R. and Pereyra, Ricio and Fernandez, Ricardo and Gonzalez-Doncel, Gaspar and Bruno, Giovanni},
  title     = {Evidence of damage evolution during creep of Al-Mg alloy using synchrotron X-ray refraction},
  series = {Journal of applied crystallography},
  volume    = {51},
  journal   = {Journal of applied crystallography},
  publisher = {International Union of Crystallography},
  address   = {Chester},
  issn      = {1600-5767},
  doi       = {10.1107/S1600576718001449},
  pages     = {420 -- 427},
  year      = {2018},
  abstract  = {In order to provide further evidence of damage mechanisms predicted by the recent solid-state transformation creep (SSTC) model, direct observation of damage accumulation during creep of Al-3.85Mg was made using synchrotron X-ray refraction. X-ray refraction techniques detect the internal specific surface (i.e. surface per unit volume) on a length scale comparable to the specimen size, but with microscopic sensitivity. A significant rise in the internal specific surface with increasing creep time was observed, providing evidence for the creation of a fine grain substructure, as predicted by the SSTC model. This substructure was also observed by scanning electron microscopy.},
  language  = {en}
}
@article{ShashevKupschLangeetal.2017,
  author    = {Shashev, Yury and Kupsch, Andreas and Lange, Axel and Evsevleev, Sergei and M{\"u}ller, Bernd R. and Osenberg, Markus and Manke, Ingo and Hentschel, Manfred P. and Bruno, Giovanni},
  title     = {Optimizing the visibility of X-ray phase grating interferometry},
  series = {Materials testing : Materialpr{\"u}fung ; materials and components, technology and application},
  volume    = {59},
  journal   = {Materials testing : Materialpr{\"u}fung ; materials and components, technology and application},
  publisher = {Hanser},
  address   = {M{\"u}nchen},
  issn      = {0025-5300},
  doi       = {10.3139/120.111097},
  pages     = {974 -- 980},
  year      = {2017},
  abstract  = {The performance of grating interferometers coming up now for imaging interfaces within materials depends on the efficiency (visibility) of their main component, namely the phase grating. Therefore, experiments with monochromatic synchrotron radiation and corresponding simulations are carried out. The visibility of a phase grating is optimized by different photon energies, varying detector to grating distances and continuous rotation of the phase grating about the grid lines. Such kind of rotation changes the projected grating shapes, and thereby the distribution profiles of phase shifts. This yields higher visibilities than derived from ideal rectangular shapes. By continuous grating rotation and variation of the propagation distance, we achieve 2D visibility maps. Such maps provide the visibility for a certain combination of grating orientation and detector position. Optimum visibilities occur at considerably smaller distances than in the standard setup.},
  language  = {en}
}
@article{ShashevKupschLangeetal.2016,
  author    = {Shashev, Yury and Kupsch, Andreas and Lange, Axel and M{\"u}ller, Bernd R. and Bruno, Giovanni},
  title     = {Improving the visibility of phase gratings for Talbot-Lau X-ray imaging},
  series = {Materials testing : Materialpr{\~A}¼fung ; materials and components, technology and application},
  volume    = {58},
  journal   = {Materials testing : Materialpr{\~A}¼fung ; materials and components, technology and application},
  publisher = {Hanser},
  address   = {M{\"u}nchen},
  issn      = {0025-5300},
  doi       = {10.3139/120.110948},
  pages     = {970 -- 974},
  year      = {2016},
  abstract  = {Talbot-Lau interferometry provides X-ray imaging techniques with significant enhancement of the radiographic contrast of weakly absorbing objects. The grating based technique allows separation of absorption, refraction and small angle scattering effects. The different efficiency of rectangular and triangular shaped phase gratings at varying detector distances is investigated. The interference patterns (Talbot carpets) are modeled for parallel monochromatic radiation and measured by synchrotron radiation. In comparison to rectangular shapes of phase gratings much higher visibility is obtained for triangular shapes which yield enhanced contrast of a glass capillary test specimen.},
  language  = {en}
}